Soil n‐alkane δ¹³C along a mountain slope as an integrator of altitude effect on plant species δ¹³C

Abstract

Carbon isotopic compositions of leaf wax‐derived n‐alkanes (δ13Cwax) and bulk organic matter (δ13CSOM) in surface soils from ca. 1000 to 3800 m above sea level along Mount Gongga, China were investigated for their altitudinal variations. There is a breakpoint, suggesting a precipitation threshold, at 2050 m in both δ13Cwax and δ13CSOM trends. Above the threshold, δ13Cwax and δ13CSOM increase in a similar pattern of the average species‐level response to altitude reported from various humid mountainous areas. However, a significant decreasing trend with altitude occurs below the threshold, within which climate changes upward from arid to humid, consistent with plant foliar δ13C response to precipitation at water‐limited areas. Because δ13Cwax and δ13CSOM naturally integrate plant species and time, this work demonstrates that the altitude‐induced environmental impact on plant species‐level δ13C has been conveyed to soils, and that the species‐level δ13C could be linearly scaled up to the community level.

Altitude effect on leaf wax carbon isotopic composition in humid tropical forests

“…Aridity leads to closure of stomata to limit transpiration, with attendant 13 C-enrichment (Cernusak et al, 2013). Thus, δ 13 C is confounded in profiles where aridity is a variable (Friend et al, 1989, Wei andJia, 2009) but not in wet catchments, such as this one and that reported by Körner et al (1991). The addition of another elevation-sensitive proxy, and especially the ability to measure two isotope systems (δ 13 C and δD) in the same leaf wax molecules, offers the possibility to cross-check aridity effects (positive correlation) versus altitude effects (negative correlation).…”

Leaf Wax δD and δ13C in Soils Record Hydrological and Environmental Information Across a Climatic Gradient in Israel

“…δ 13 C wax of C 4 plants in a transect in Cameroon show no correlation with rainfall or humidity (Garcin et al, ). Soil δ 13 C wax from the Cameroon transect shows a weak significant correlation with relative humidity (Schwab et al, ), and those from a transect in China show an altitude effect similar to that in bulk δ 13 C (Wei & Jia, ). Whether these finding are applicable to regions beyond those studied is something we investigate here.…”

Driving forces of mid-Holocene vegetation shifts on the upper Tibetan Plateau, with emphasis on changes in atmospheric CO2 concentrations

“…Hence, the central physiological adaptations to dry ecosystems and to high altitudes (i.e. low leaf nitrogen-use efficiency and high water-use efficiency) are similar and such adaptations are demonstrated in gradient studies of Tibetan vegetation Wei and Jia, 2009). Experimental and modelling investigations have shown that plant-growth response to elevated CO 2 concentrations is amplified in vegetation types with high nitrogen but limited water supply McMurtrie et al, 2008).…”

“…However, the photosynthetic capacity of alpine plants is not correspondingly lowered, probably as a result of physiological adaptation and acclimation, thereby accepting higher energetic costs to compensate for the low efficiency of physiological processes at high altitudes (Reich and Oleksyn, 2004). High-alpine plants have high leaf nitrogen concentrations indicating lower plant nitrogen-use efficiency (for the Tibetan Plateau, see He et al, 2006) and low water-use efficiency (Körner et al, 1988; for Tibetan Plateau, see Wei and Jia, 2009). Thus plants with xeromorphic leaf anatomies such as increased stomatal densities (Pyankov and Kondrachuk, 2003) are at a competitive advantage.…”